1. Field of the Invention
The present invention relates to a process of producing an aromatic aldehyde such as p-tolualdehyde by reacting the appropriate alkylbenzene with carbon monoxide in presence of a Ta, Nb, or Sb pentafluoride-hydrogen fluoride catalyst system.
A number of processes have been proposed to produce aromatic aldehydes such as para-tolualdehyde. For the most part, these methods involve reacting the alkyl-substituted benzene, such as toluene with carbon monoxide in presence of some type of a catalyst system. However, while such methods have proven to be useful, they suffer from one or more process deficiencies. For example, in some instances processes of this type necessarily involve resort to subambient temperatures, which, of course, involves some considerable process control. In other cases, large excesses of catalyst must necessarily be employed to carry out the synthesis to obtain appreciable yields. In still other instances, useful catalysts in this reaction are highly corrosive leading to obvious problems. Lastly, in some cases, the reaction is effected only at relatively high pressures.
Typical prior art references involving carbonylation of aromatic hydrocarbons such as toulene include U.S. Pat. Nos. 1,197,682; 2,485,237; and 3,948,998 and German Patent Nos. 2,422,197; and 2,460,673; and British Patent No. 1,422,308.
It therefore becomes an object of the invention to provide a process for producing aromatic aldehydes such as para-tolualdehyde by means which eliminate the above discussed disadvantages and others.
Other objects will appear hereinafter.